Dehydrogenation catalysts comprising bismuth compounds on macroporous supports



United States Patent' Oflice 3,409,696 Patented Nov. 5, 1968 s 12Claims. o. 260680) ABSTRACT OF THE DISCLOSURE Dehydrogenation ofhydrocarbons is effected in the presence of steam and a catalyst whichcomprises at least one bismuth compound supported on an inorganicphosphate of a Group II metal, the support having a macroporousstructure.

The present invention relates to new and effective catalysts for use incertain hydrocarbon dehydrogenation reactions and to the use of suchcatalysts in such reactions.

The catalysts of the present invention derive their activity from thepresence therein of a bismuth compound. It was previously known thatbismuth compounds could be used for stabilizing catalyst materialswhich, in themselves, had dehydrogenating activity, for example, smallproportions of bismuth oxide have been incorporated as stabilizers indehydrogenation catalysts comprising iron oxide, chromium oxide and apotassium compound. It is also known to use compounds containing bothbismuth and their metals such as molybdenum and tungsten, for example,bismuth tungstate, bismuth molybdate, bismuth phosphotungstate andbismuth phosphomolybdate, either as such or on inert supports, ashydrocarbon oxidation catalysts but these catalysts were reported torequire the presence of molecular oxygen to be effective. The presenceof molecular oxygen was also reported to be required to obtain usefulhydrocarbon oxidation activity in the known use of bismuth phosphate.This known use of unsupported bismuth compounds also has thedisadvantage that pellets of such unsupported bismuth compounds shrinkduring use and rapidly lose their activity. It has also been reportedthat other bismuth compounds, particularly bismuth oxide, have, inthemselves or on inert supports, no dehydrogenating activity.

The present invention is based on our surprising discovery that it ispossible to prepare useful hydrocarbon dehydrogenation catalysts whichare effective for prolonged operation irrespective of Whether or notmolecular oxygen is present, using any bismuth compound. These catalystsare obtained using one or more bismuth compounds in conjunction withcertain supports. The supports which can be used in the catalysts of thepresent invention are broadly defined as those in which at least 60% ofthe total pore volume of said support is contributed by pores havingdiameters in the range of from 1000 to 8000 Angstrom units (A.).

Accordingly, the present invention provides a hydrocarbondehydrogenation catalyst comprising at least one bismuth compound on asupport in which at least 60% of the total pore volume of said supportis contributed by pores having diameters in the range of from 1000 to8000 A.

Any supports may be used in the catalysts of the present inventionprovided that they comply with the aforesaid pore size distributionrequirement. The supports used in the catalysts of the inventionpreferably have at least 80% of their total pore volume contributed bypores with diameters in the range of from 1000 to 8000 A., and mofepreferably with at least 90% of their total pore volume contributed bypores with diameters in the range of from 1000 to 6000 A.

It has been fund that particularly useful catalysts can be provided withsupports which are inorganic phosphates, particularly phosphates of aGroup II metal. Examples of suitable supports are calcium phosphate andmagnesium phosphate. Active catalysts have also been prepared usingsintered alumina supports which comply with the above pore sizedistribution requirements.

The extent to which the bismuth compound or compounds may be used on thesupport will depend on the nature of the bismuth compound and thesupports and on the particular hydrocarbon dehydrogenation process inwhich it is intended to use the resulting catalyst. The amount ofbismuth compound used also depends to some extent on the procedureadopted for incorporating it into the catalyst. Useful catalysts havebeen obtained with amounts as small as 2% and as large as by weightbased on the total catalyst composition. In general the bismuthcompounds are incorporated to the extent of from 1 to by weight based onthe total catalyst composition.

The method by which the bismuth compound or compounds are incorporatedin the support will also depend upon the natures of the bismuth compoundor compounds and the support. In many cases, it has proved satisfactoryto form the catalysts by simple dry mixing of the bismuth compound orcompounds with the supports. Alternatively, when the catalyst componentsare prepared in a wet form, the mixing may be effected prior to dryingthe components. In the case of catalysts prepared by simple admixture ofthe bismuth compound with the support, it is preferred to use thebismuth compound or compounds to the extent of from about 5 to about 60%and more preferably to the extent of from about 20 to about 60% byweight based on the total catalyst composition. In the case ofincorporation by simple admixture, particularly satisfactory resultshave been obtained by the use of bismuth oxide or a compound capable offorming a bismuth oxide under the hydrocarbon dehydrogenation processconditions. Such bismuth oxide formation may also occur during theregeneration operation described below. Examples of the preferredbismuth compounds for use in the catalysts of the present invention arebismuth oxide, bismuth hydroxide, bismuth phosphate, and bismuthphosphomolybdate.

A further method for incorporating the bismuth compounds involvesimpregnating a preformed support with an acidic solution of the bismuthcompound or compunds. This procedure cannot be used for supports whichwould be adversely affected by the acidic solution but has provedsatisfactory with acid-resistant supports such as sintered alumina.

If desired, the catalysts of the invention may be modified forparticular applications by the incorporation of other active or inactivematerials. Some improvement in activity has, for instance, been noted onthe incorporation of small proportions, for example, 0.5 to 5% by weightof chromic oxide in catalysts with calcium phosphate supports.

The catalysts of the present invention can be used in any conventionaldehydrogenation reactions but are particularly useful in thedehydrogenation, both in the absence and the presence of molecularoxygen, of at least one hydrocarbon selected from aliphatic monoolefinshaving at least four and preferably four to six carbon atoms in theirunsaturated carbon chains, alkylated aromatic hydrocarbons having atlesat two and preferably two to four carbon atoms in their alkyl groups,cycloaliphatic olefins having five to eight carbon atoms in theirolefinically unsaturated rings and cycloalkanes having five to sevencarbon atoms. In accordance with standard practice, references herein tothe unsaturated carbon chain of a monoolefin denote the longest carbonchain which contains the olefinic double bond.

The catalysts of the present invention are especially useful for thedehydrogenation of butene-l and/or butene-2 to butadiene, of isoamyleneto isoprene, and of ethyl benzene to styrene. They can also be appliedto the dehydrogenation of a mixed olefin feed stock such as a mixture ofn-butene and isoamylene.

'The catalysts of the present invention are also useful for thedehydrogenation, in the presence of molecular oxygen of paraflinichydrocarbons containing at least three and preferably three to eightcarbon atoms, particularly for the dehydrogenation of butane to butenesand butadiene.

Hydrocarbon dehydrogenation reactions using the novel catalysts of theinvention are preferably carried out at elevated temperature in thepresence of steam. It should be noted that these reactions must not beeffected at a temperature at which the pore size distribution of thesupport would deviate substantially from the limitations set down above.It should also be noted that the supports may only conform to the poresize distribution requirements after they have been heated to anelevated temperature. For instance, in the case of calcium phosphate, itis necessary for it to be heated, for example, at a temperature of about650 C. for about 16 hours or more, to obtain the desired pore sizedistribution. Since the pore size limitations apply to the supportitself, the temperature to which any such catalyst mixture should beheated will first be determined on a separate sample before theincorporation of the bismuth compound or compounds even though theactual heating will be effected on the whole catalyst composition. Itmust be stressed that the pore size limitations apply to the supportafter any heat treatment and not to the whole catalyst composition whichwill generally have a completely different pore size distribution.

Dehydrogenation reactions using the novel catalysts of the invention aregenerally carried out at temperatures between 500 C. and 750 C. or attemperatures not greatly outside this range. Such dehydrogenation ispreferably effected at temperatures between 500 and 650 C.

As previously stated, the dehydrogenation reaction is preferably carriedout in the presence of steam and the amount of steam is generallybetween 5 and 40, prefet ably between and 25, volumes per volume ofhydrocarbon although smaller or larger proportions may be used ifdesired.

Except for the foregoing limitations, the hydrocarbon dehydrogenationconditions may be varied widely. For instance, the method is operable atwidely varying flow rates, although the rates of flow should, of course,be sufficient to avoid excessive decomposition of the dehydrogenatedproduct.

For fixed bed operation, the catalysts of the present invention arepreferably used in the form of pills, tablets or pellets of a suitablesize and such pellets may be formed from a powdered material byadmixture with a lubricant such as graphite, a vegetable oil or ahydrocarbon oil which may subsequently be removed by vaporization oroxidation. To prepare these new catalysts for use in hydrocarbondehydrogenation processes, the reaction chamber is charged with thegranular catalysts and the lubricant, if used, is burnt off by passingair or preferably a mixture of up to about 50% air with steam, throughthe catalyst bed at an elevated temperature. When the lubricant used forpreparing the catalyst pellets is a substance capable of beingvaporized, e.g., a mineral oil or vegetable oil, the burn-off treatmentwith air and steam may be preceded by one of passing an inert gas suchas steam, nitrogen or carbon dioxide over the catalyst at a temperatureof from ZOO-600 C. so as to vaporize at least a portion of the bindingagent from the catalyst granules. Obviously, steam will not be passedthrough the catalyst bed until the temperature of the latter exceeds thetemperature at which the steam would condense thereon. As previouslyindicated, the desired pore size distribution of some supports may onlybe obtained after the catalyst composition has been heated. Thenecessary modification of the pore size distribution may, therefore, beeffected during the lubricant-removal operation and/or in a separateheat treatment operation following the lubricantremoval operation.

After freeing the catalyst of the lubricant, the catalyst bed isgenerally swept free of air with steam and is heated to the desiredreaction temperature, preferably by passing superheated steam throughthe bed. The mixture of steam and the hydrocarbon feed, optionally withoxygen, is then passed through the catalyst bed at the desiredtemperature. The usual procedure is to pass the hydrocarbon feed intoadmixture with steam which has been superheated to a temperaturesufficient for the reactant mixture to be at the desired reactiontemperature, and to pass the resulting mixture through the catalyst bed.However, the heat may be supplied in other ways. The vapours issuingfrom the catalyst chambers are ordinarily passed through heat exchangersand through cooling devices, first to condense the steam and then toseparate the product.

During use in hydrocarbon dehydrogenation reactions, the catalysts ofthe present invention may gradually accumulate a small amount of carbonor nonvolatile organic material and consequently lose their catalyticactivity. To regenerate such catalysts, the flow of hydrocarbon startingmaterial is periodically interrupted and air admixed with steam is blownthrough the catalyst bed at a suitable elevated temperature, forexample, at a temperature 500 and 750 C., to oxidize and remove thecarbonaceous or organic material. The duration of the catalystregeneration period is related to the duration of the precedingdehydrogenation period. In general, the catalysts will be used in acyclic operation comprising alternate dehydrogenation and regenerationoperations.

For some supports, there may be a temperature above which the supportcannot be heated without loss of the required pore size distribution. Insuch a case, the catalyst will not be heated above such a temperature inany of the operating stages, i.e., the lubricant-removal operation, anyseparate heat treatment operation, the actual dehydrogenation operationand the regeneration treatment. In addition, it is undesirable to heatthe catalysts to such a temperature that the bismuth compound orcompounds melt or are converted to bismuth metal. In the case of bismuthoxide-containing catalysts, temperatures greater than about 820 C. willnot normally be used.

The invention will now be illustrated in the following examples inwhich, unless otherwise stated, all parts and percentages are by weight.

EXAMPLE 1 6.7 litres of an aqueous solution containing 462 g./ litre ofcalcium chloride were filtered and 2333 g. of orthophosphoric acid werethen added, thereby giving approximately 8.7% excess phosphoric acidover the amount which would be required to form calcium phosphate. Thesolution was then made up to 12.0 litres with distilled water. Thisstock solution was then fed at the rate of 5.5 ml. per minute into a 600ml. beaker where it was diluted with water and, from which it was fed,after dilution, into a glass reaction vessel at the rate ofapproximately ml. per minute, the reaction vessel having a capacity of15 litres, being maintained at a temeprature of 25 C., and being fittedwith a propeller type mixer and bafiles for producing turbulence.

An aqueous ammonium hydroxide solution containing 14% v./v. NH was fedinto the reaction vessel so that the pH of the agitated mixture wasmaintained at 8.0.

6 The resulting slurry was agitated and allowed to over- From theseresults, it will be seen that the calcium flow from the reaction vesseland to run to waste until phosphate of Test No. 1 does not conform tothe pore steady state conditions were established. The overflowing sizedistribution requirements for supports according to slurry was thencollected in a settling tank for a period the invention, in not havingat least 60% of its total pore of 16 hours and then allowed to settle incontact with the volume contributed by pores with diameters in the rangeprecipitation mother liquor for a further period of 24 of from 1000 to8000 A.

hours, after which the mother liquor was decanted from Several catalystswere prepared by mixing 50 parts of the settling tank and the settledslurry was filtered and the calcium phosphate, after removal from thedrying washed with distilled water. The washed filter cake was oven,with varying proportions of bismuth oxide. The rethen mulled for onehalf hour without any heating and sulting mixtures were then mixed with2% graphite, and then for a few minutes with distilled water. Theresulting in one case with 2% chromic oxide, pelleted and the slurry wasthen refiltered and washed with distilled water. graphite-removaloperation performed under the condi- The washing treatment comprisingthe mulling, filtering tions set down in Table 1.

and washing operations was then repeated three times. After the removalof the graphite, the catalytic activi- The filter residue was then r d tt mullet Where ties of the pellets for the dehydrogenation of butene-lit Was Partially dried 3 Period of 11/1 hours With a 15 were determinedat the temperatures specified in Table 2. P- Steam Pressure Th6 P Y f fwas The activity determinations were effected using mixtures thentoransfened to trays and dned Ovemlgm an Over) of steam and butene-l inthe approximate relative proporat 65 The oven temperature was thenIncreased to tion of volumes of steam per volume of hydrocarbon.

300 C. and the drying operation was terminated three 20 Thedehydrogenation product was analyzed by gas hours after the commencementof the oven temperature Chromatography, no account being taken of theformation rise from 65 C.

of carbonyls or coke. After removal from the oven, a portion of thematerial The percent conversion (%C) as expressed by 100 was ground byhand to pass through a Tyler Standard 10 mesh sieve and then thoroughlymixed by hand with 2% times the number of moles pentene-l converteddivided by the total number of moles of butene-l 1n the feed, the

graphite. The mixture was then formed into cylindrical pellets ofdiameter and length and having Sha1 percent selectivlty (%S) asexpressed by 100t1mes the lowconvex ends. number of moles of butene-lconverted to butadiene, di-

The removal of the graphite was effected at different Vided by the totalnumber of moles of 'blltene-l reacted, temperatures and for varyingtimes by passing a mixture and the P yield as expressed y the P of steamand air over approximately 23 of h pellets net of the percent conversionand the percent selectivat the following flow t ity were calculated.Several tests were made and the results obtained are given in Table 2.

A further series of activity determinations was made in the same mannerexcept that 25% by volume of free oxygen based on the butene-l was addedto the feed. The mean results of several determinations are given inAfter this treatment, the pore size distributions of the Table pelletswere determined by th mercury penetration 40 Dehydrogenation activitieswere also determined for method and the results given in Table 1 wereobtained. Pellets Prepared from unsupported bismuth 0Xid8 and for Themercury penetration method is described in an article calciumP11951911?!te containing no bismuth OXide- In the by H. L. Ritter and L.c. Drake, Ind. and Eng. Chem., case of the unsupported bismuth oxide. ec i y d Anal. Ed 17, N0, 12, 782.786, 1945, Th pore si di terminationwas efiected on unpelleted material, whilst, tribution determinationswere made at a maximum merin t C f the is ut -f e Cal ium phosphate, the

, Ml./minute Steam (calculated at room temperature and pres- 35 sure)2000 Air (measured at room temperature and pressure)- 100 cury pressureof 3000 p.s.i. pellets were formed using 2% graphite, no chromic oxideTABLE 1.PORE SIZE DISTRIBUTIONS OF CALCIUM PHOSPHATE PELLETS AFTERDIFFERENT GRAPHITE-REMOVAL OPERATIONS Graphite- Test removal Pore sizedistribution-percentage of total pore volume from pores of specifieddiameters No. conditions HIS. C. l,000 A. 1,000- 2,000 3,000- 4,0005,000- 6,000 7,000- 8,000- 9,000 10,000 A. 1,000- 1,000-

2,000 A. 3,000 A. 4,000 A. 5,000 A. 6,000 A. 7,000 A. 8,000 A. 9,000 A.10,000 A. 8,000 A. 6,000 A; 602 80. 3 19. 7 0 0 0 0 0 0 0 0 0 19. 7 19.7 650 2. 1 94. 5 2. 2 2. 2 0. 3 0. 3 0. 2 0. 2 0. 7 0. 7 0. 7 97. 2 97.0 811 0 3. 8 17. 7 28. 5 29. 9 11. 8 1. 4 1. 0 1. 0 1. 0 4. 9 94. 1 91.7 790 0 0 6. 6 35. 0 29. 2 12. 4 5. 8 2. 2 1. 5 1. 5 5. 8 91. 2 83. 2

being included, and the graphite-removal operation was elfected for 16hours at 650 C.

TABLE 2.NON-OXIDATIVE DEHYDRO GENATION OF BUTENE-l WITH CALCIUMPHOSPHATE, BISMUTH OXIDE AND CALCIUM PHO SPHATE/BISMUTH OXIDE CATALYSTSGraphite Pore size Temperature of dehydrogenation activitydeterminations Catalyst Composition removal (diameter) distri- Testconditions bution* (percent) 600 0. 620 0. 650 C.

02. (104); B1203 CrzOa hrs. O. 1,000 1,000- %C S %Y %C %S %Y %C %S %Y100 0 0 16 650 97.2 97 0 3. 6 91.0 3. 3 6. 5 89. 0 5. 8 0 100 0 Inactiveat all temperatures tested, even after heating at 650 C. 50 0 16 602 19.7 19. 7 55. 9 61. 6 34. 4 56. 0 66. S 37. 4 50 50 0 16 650 97.2 97. 034. 2 68.8 23. 5 56. 1 68. 7 38. 5 50 50 0 16% 811 94. 1 91. 7 29. 5 73.6 21. 7 38. 9 68 9 50 50 0 64 790 91.2 83. 2 22. 5 81. 3 18. 3 36. 0 800 50 50 2 16 650 97.2 97. 0 87. 9 70.9 26. 9 25 0 16 650 97. 2 97. 0 38.2 67.8 25. 9 52. 5 66.8

The pore size distributionresults are quoted from Table 1 and apply tothe bismuth-tree calcium phosphate after the graphite-removal operatiomTABLE 3.-OXIDATIVE DEHYDROGENATION (25% vjvJggTqkFLilsigflNE-l WITHCALCIUM PHOSPHATEIBISMUTH OXIDE Dehydrogenation activity Graphite- Poresize (diameter) determination temperature Test Calalyst removaldistribution (pereent) N 0. Composition conditions 600 0. 650 C.

1,000- 1,000- Co3(PO4)2 BizO; CrzOs hrs. C. 8,000 A. 6,000 A. %C %S %Y%C %S %Y *The pore size distribution results are quoted irom Table 1 andapply to the bismuth'iree calcium phosphate after the graphite-removaloperation.

'From these results, it will be seen that calcium phosphate having apore size distribution conforming to the broad requirements of theinvention (Test No. 2) in itself shows substantially no dehydrogenationactivity. Test No. 5 showed that unsupported bismuth oxide also hassubstantially no catalytic activity. Although the support itself andbismuth oxide are both substantially inactive, it will be seen from theresultsiof Tests Nos. 7 and to 13 that, when the bismuth oxide issupported on the cal cium phosphate, the resultant catalyst exhibitssubstantial dehydrogenation activity in both the absence and presence ofmolecular oxygen.

The results of Tests Nos. 10 and 13 show that a small proportion ofchromic oxide may optionally be included in the catalysts of the presentinvention having calcium phosphate supports.

It will be seen that, although the support of Test No. 6 was outside thedefinition of those which can be used in the catalysts of the invention,the catalyst prepared from such a support apparently exhibitedsubstantial dehydrogenation activity. This catalyst was, however,unstable, metallic bismuth being formed on the surface of the catalystpellets during use. Such a catalyst is consequently considered to beunsuitable for use in accordance with the present invention indehydrogenation reactions.

It should also be noted that the support used in Test No. 9 met thebroad and preferred requirements for the present invention but that itdid not comply with the more preferred requirement of having at least90% of its total pore volume contributed by pores with diameters in therange of from 1000 to 6000 A. It will be noted that the catalystprepared from such support showed somewhat reduced activity compared tothat used in Tests Nos. 7 and 8 which did in fact comply with the morepreferred pore size distribution requirements.

EXAMPLE 2 A further catalyst was prepared as described for Test No. 2 inExample 1, except that 25 parts of bismuth phosphate were mixed with 75parts of the calcium phosphate, together with the 2 parts of graphiteand 2 parts of chromic oxide. The activity of this catalyst for thedehydrogenation of butene-l was determined (after removal of thegraphite by heating for 16 hours at 650 C.) as generally described inExample 1 in the presence of 10% v./v. oxygen in a 17-day continuouscyclic process, each cycle comprising alternating 5 minutedehydrogenation and 5 minute regeneration steps, the regeneration beingeffected with a mixture of 420 v./v./ hr. of air and 2300 v./v./hr. ofsteam. The results given in Table 4 indicate the activities at variousstages during the test.

TABLE 4.OXIDATIVE DEHYDROGENATION (10% V./V. 02)

0F BUTENE-l USING A BISMUTH PHOSPHATE/CALCIUM PHOSPHATE CATALYST Theseresults indicate that the catalyst had a substantially highdehydrogenation activity, even after 17 days continuous operation.

A similar catalyst was prepared from parts bismuth phosphate and 50parts calcium phosphate, followed by the addition of 2 parts of graphiteand ,2 parts of chromic oxide. The graphite was removed by heating for16 hours at 650 C. and this catalyst was evaluated in thedehydrogenation of ethyl benzene to styrene. The following results wereobtained at a dehydrogenation temperature of 625 C.

Test No. 17

Percent Conversion of ethyl benzene 29.4 Selectivity (styrene obtainedexpressed as percentage of ethyl benzene converted) 65.9 Yield (styreneobtained expressed as percentage of ethyl benzene fed to reactor) 19.4

These results indicate that catalysts according to the present inventionare active in the dehydrogenation of alkylated aromatic hydrocarbonssuch as ethyl benzene.

EXAMPLE 3 Test No. 18

Percent Conversion 48.0 Selectivity 96.1 Yield 46.1

It will be seen that the bismuth phosphomolybdate/calcium phosphatecatalyst had substantial dehydrogenation activ ty even though thecalcium phosphate itself is sub stantially inactive (Test No. 2).

EXAMPLE 4 A further catalyst was prepared as described for Test No. 2 inExample 1 except that 50 parts of bismuth hydroxide were mixed with50parts of the calcium phosphate together with the 2 parts of graphite.After removal of the graphite by heating for 16 hours at 650 C., thiscatalyst was evaluated in the dehydrogenation of butene-l in the mannerdescribed in Example 1 in both the absence and the presence of 25% byvolume of oxygen (based on the butene-l). The resultsobtained are givenin Tables 5 and '6.

TABLE 5.NON-OXIDATIVE DEHYDROGENATION OF BUTENE-l USING A BISMUTHHYDROXIDE/CALCIUM PHOSPHATE CATALYST Catalyst Composition Test No.

TABLE GfOXIDATIVE DEHYDROGENATION (25% v./v Test No. 23.-Oxidativedehydrogenation (25% v./v. 0 OF BUTENE-l USING A BISMUTHHYDRQXIDE/GALCIUM of butene-l PHOSPHATE CATALYST DehydrogenationTemperature Catalyst: Mg (P0 Bi 0 C1' O (5 0/ 5 0/ 2) Dehydrogenationtemperature: 620 C.

Catalyst Composition Test No. 600 0. 650 C. .6

Conversion: 41.4%. 023(104): Bi(OH)s %0. %S %Y %C Selectivity. 75 50 5048.4 68.1 33.0 50.9 71.0 36.1 Yield: 31.3%.

These results indicate the catalytic activity of yet From these results,it will be seen that this magnesium another catalyst according to thepresent invention. The phosphate-supported catalyst possessedsubstantial dehysubstantially complete inactivity of calcium phosphatehas drogenation activity. already been noted (Test No. 2). EXAMPLE 6EXAMPLE 5 'Magnesium phosphate was prepared in exactly the sameCatalysts were Prepared y impregnation 0f the followmanner as describedin Example 1 for the preparation iflg pp materials! I,

of calcium phosphate except that, instead of atotal weight A 'f alumln'athe form of dlametel or 3095 g. of calcium chloride (6.7 litres of a 462g./litre pellets and h l gal; H

solution), 5670 g. of magnesium chloride (12 litres of a Extrudedcyllndrlcal $111901! cafblde P 716 473 g. magnesium chloride hexahydrateper litre solu- 20 dlameter andlellgth); f

fi were used (c) Extruded cylindrical s1l1ca pellets dlameterTheresulting magnesium phosphate was ground by and s l hand to passthrough a Tyler Standard 10 mesh sieve and h lmpregnatlon of thesemammals s effected by then thoroughly mixed by hand with graphite Thesoaking a weighed quant ty of pellets for 10 minutes in a mixture wasthen formed into cylindrical pellets of f' aqueous solutlon of blsmufl}mate diameter and s5 length and having shallow convex ends nitric ac d.After removal from the solutlon, the wet pellets The graphite was nextremoved from a 23 g. sample were dried and then heated for a period of 5hours at a of these pellets generally in the manner described inExtemperature of 600-700 lmpregnatlon ample 1 by passing a mixture ofsteam and air over them 3 procedure was then repeated once, after whichthe amount for 16 hours at 650 C. i of bismuth retained by the pelletsas bismuth oxide was After thi tre t t, th pore i di ib i f h calculatedfrom the weight increase and expressed as a pellets was determined bythe mercury penetration method Percentage 0f the total Weightand theresults given in Table 7 were obtained. The pore size distributions ofseparate samples of each TABLE 7.PORE SIZE DISTRIBUTION OFMAGNESIZlggTRPfiOHSgEfigE PELLETS AFTER GRAPHITE-REMOVAL AT 650 C.

Pore size distribution-percentage of total pore volume from pores ofspecified diameters Test 1,000 A. 1,000 2,000- 3,000 4,000- 5,000 6,000-7,000 8,000- 9,000 10,000 A. 1,000- 1,000- NO. 2,000 A. 3,000 A. 4,000A. 5,000 A. 6,000 A. 7,000 A. 8,000 A. 9,000 A. 10,000 A. 8,000 A. 6,000A.

A catalyst was next prepared by mixing 50 parts of the of the supportmaterials were then determined by the mer- 'ground magnesium phosphatewith 50 parts of bismuth cury penetration method.

oxide. The resulting mixture was then mixed with 2 parts Thedehydrogenation activities of the impregnated sup- -graphiteand 2 partschromic oxide, pelleted and the ports for the dehydrogenation ofbutene-l were deter- :graphite removed as previously described for 16hours at mined in the manner generally described in Example 1 in 650 C.The activity of the resulting catalyst for the dethe absence of oxygenat 600 C. A dehydrogenation achydrogenation of butene-l was thendetermined genertivity determination was also made on the bismuth-free-ally as described in Example 1, both in the absence of sintered aluminasupport. The pore size distribution re- ':oxygenand in the presence of25% v./v. oxygen based on the butene-l. The results obtained are givenbelow.

TABLE 8.-NON-OXIDATIVE DEHYD R0 GENATION OF BUTENE-l WITH A MAGNESIUMPHOSPHATEIBISMUTH OXIDE CATALYST Dehydrogenation temperature TestCatalyst Composition No.

sults are .given in Table 9 and the dehydrogenation activities are givenin Table 10.

TABLE 9.-PO RE SIZE DISTRIBUTIONS OF VARIOUS CATALYST SUPPO RTS Poresize distributions-percentage of total pore volume from pores ofspecified diameters Test Support N0. 1,000 A. 1,000 2,000- 3,000- 4,000-5,000- 6,000- 7,000 8,000 A. 1,000- 1,000-

2,000 A. 3,000 A. 4,000 A. 5,000 A. 6,000 A. 7,000 A. 8,000 A. 8,000 A6,000 A.

24 sintered alumina 3. 0 66. 8 66. 8 66. 8 l6. 1 16. l 10. 6 l0. 6 3. 593. 5 82. 9 25 Extruded silicon carbide" 0 0 0 0 0 0 0 0 99 0 0 26Extruded silica 0 0 0 0 0 0 0 0 99 0 0 IMPREGNA'IED CATALYSTS Pore size(diame- Dohydrogenation activity Catalyst description ter) distribution7 Test No. (percent) Support Bismuth content 1,000- l,000 7 C 7 S Y(Percent BizOa) 8,000 A. 0,000 A.

24 Sintered alumina None 93. 5 82. 9 Negligible 27 do 16. 4 93. 5 82. 938. 8 45. 8 17. 8 28 Extruded silicon carbide... 17.8 0 4. 3 53. 1 2; 3T 29 Extruded silica 23. 8 0 0 4. 0 58. 2.3

The pore size distribution values are quoted from Table 9 and apply tothe bisumth-iree supports.

From these results, it is readily seen that the only support of thosetested which conforms to the pore size distribution requirements setdown for use in the catalysts of the present invention is the sinteredalumina one (Tests Nos. 24 and 27). It is also readily seen that thismaterial has, in itself, no significant dehydrogenation activity (TestNo. 24) but, when impregnated so as to contain 16.4% 'bismuth'oxide, theresultant catalyst has significant activity, Test No. 27). Neither ofthe other supports tested conformed to the pore size distributionrequirements for supports for the catalysts of the present inventionand, when impregnated with a bismuth compound, neither showed anysignificant dehydrogenation activity (Tests Nos. 28 and 29).

We claim:

1. A hydrocarbon dehydrogenation catalyst comprising from 1 to 80% byWeight of at least one bismuth compound on a support of which at least80% of the total pore volume is contributed by pores having diameters inthe range of firom 1,000 to 8,000 A., said support comprising calciumphosphate or magnesium phosphate.

2. A catalyst according to claim 1 comprising from 5 to 60% by weight ofa bismuth compound selected from the group consisting of bismuth oxide,bismuth hydroxide, bismuth phosphate and :bisrnuth phosphomolybdate.

3. A catalyst according to claim 2 in which at least 80% of the totalpore volume of the support is contributed by pores having diameters inthe range of from 1,000 to 8,000 A.

4. A catalyst according to claim 3 in which at least 90% of the totalpore volume of the support is contributed by pores having diameters inthe range of from 1000 to 6000 A.

5. A process for the dehydrogenation of a hydrocarbon feed comprising atleast one hydrocarbon selected from aliphatic monoolefins having atleast four carbon atoms in their unsaturated carbon chains, alkylatedaromatic hydrocarbons having at least two carbon atoms in their alkylgroups, cycloaliphatic olefins having five to eight carbon atoms intheir olefinically unsaturated rings, and cycloalkanes having five toseven carbon atoms, which process comprises effecting thedehydrogenation in the presence of a catalyst comprising from 1 to 80%by weight of at least one bismuth compound on a support of which atleast 80% of the total pore volume is contributed 'by pores havingdiameters in the range of from 1,000 to 8,000 A., said supportcomprising calcium phosphate or magnesium phosphate.

6. A process according to claim 5 for the dehydrogenation of ahydrocarbon feed comprising at least one hydrocarbon selected from thegroup consisting of aliphatic monoolefins having four to six carbonatoms in their unsaturated carbon chains, alkylated aromatichydrocarbons having two to tour carbon atoms in their alkyl groups,cycloaliphatic olefins having five to eight carbon atoms in theirolefinically unsaturated rings, and'cyclo alkanes having five to sevencarbon atoms, which process comprises effecting the dehydrogenation inthe presence of steam and at temperatures between 500 and .750? C.

7. A process according to claim 6 which comprises effecting thedehydrogenation in the presence of from 10 to 25 volumes of steam pervolume of hydrocarbon and at temperatures between 500 and 650 C; I l

8. A process according to claim 7 in which the catalyst contains from 20to 60% of a bismuth compound selected from bismuth oxide, bismuthhydroxide, bismuth phosphate and bismuth phosphomolybdate.

9. A process according to claim 8 for the dehydrogena tion of ahydrocarbon feed comprising at least one n-butene.

10. A process according to claim 9 for the dehydrogenation of ahydrocarbon feed comprising at leastone nbutene, and in which thecatalyst additionally contains from 0.5 to 5% by weight of chromicoxide.

11. A process for the dehydrogenation of a hydrocarbon feed comprisingat least one hydrocarbon selected from the group consisting of aliphaticmonoolefins having four to six carbon atoms in their unsaturated carbonchains, alkylated aromatic hydrocarbonshaving two to four carbon atomsin their alkyl groups, cycloaliphatic olefins having five to eightcarbon atoms in their olefinically unsaturated rings, and cycloalkaneshaving five to seven carbon atoms, which process comprises effecting thedehydrogenation in the presence of from 10 to 25 volumes of steam pervolume 'of hydrocarbon'ali'd 'at a temperature between 500 and 650 C.,and in the presence of a catalyst which contains 20 to 60%v by weight ofat least one bismuth compound selected from the group consisting ofbismuth oxide, bismuth hydroxide, bismuth phosphate and bismuthphosphomolybdate, and a calcium phosphate support-of which :at least 90%of the total pore volume is contributed by pores having diameters in therange of from 1,000 to 6,000 A.

12. A process according to claim 11 in which the catalyst also containsfrom 0.5 to 5% by weight .of chromic oxide.

References Cited UNITED STATES PATENTS 2,684,951 7/1954 Mottern 252 1611X 2,991,321 7/1961 Voge et a1 260-680 2,991,322 7/1961 Armstrong etal.260-680 3,157,688 11/1964 Arnold er al. 252-.464 X 3,260,753 7/1966McDaniel t al 252 1 43 3,320,330 5/1967 Callahan et al 260--680 PAUL M.COUGHLAN, 111., Primary Examiner.

